The overall aim of this project is to investigate the mechanism of biological transalkylation reactions, and to use these data to design mechanism-based enzyme inhibitors of selected alkyl transferases. Thus, we use the techniques of synthetic organic chemistry, enzymology, biochemistry, and cell biology to achieve our goals. This approach has enabled us to obtain detailed mechanistic information on non-enzymic and enzyme-catalyzed methylation and aminopropylation reactions, from which we have designed metabolic stable inhibitors of enzyme-catalyzed methyl transfer and aminopropyl transfer. In the coming period of support, we wish to continue this type of approach. We will be investigating the solution kinetics of model reactions, studying spectral and stereo-chemical probes of enzyme reactions, synthesizing a new class of potential transition-state analog inhibitors of catechol-O-methyl transferase, and employing both purified enzymes and cells in culture to assay the effectiveness of our new inhibitors. We anticipate that studies of this type will lead to new highly specific medicinal agents which will inhibit only one of many transalkylation reaction in vivo. For example, in catecholamine metabolism, we should be able to obtain new drugs which will specifically inhibit the 0-methylation of norepinephrine, while not affecting the ability of the cell to N-methylate norepinephrine. These highly specific inhibitors will then be investigated for use as pharmacological and biochemical tools, and for use as drugs in the treatment of diseases for which transalkylation is thought to be an aberrant pathway. Since methylation is one common method of inactivating drugs (e.g. DOPA), new specific mechanism-based inhibitors of methylases might also serve to increase the lifetime and efficacy of agents already in clinical use.